Delaware Department of Natural Resources and Environmental Control
Leipsic River Watershed Proposed TMDLs
Arden Claymont Wilmington Bellefonte
Newark
New Castle
Delaware City
Odessa Middletown
Smyrna Clayton 13 Leipsic Kenton Cheswold Dupont Manor Hartly Dover Little Creek
Bowers
Frederica
Houston Harrington Slaughter Beach
Greenwood Ellendale Milton Lewes
Bridgeville
Rehoboth Beach
Millsboro Bethel Dagsboro Bethany Beach Frankford South Bethany
Selbyville Fenwick Island
DNRE007 August 2006 PREFACE
The draft Proposed TMDLs for the Leipsic River watershed were reviewed during a public workshop held on 11 May, 2006. All comments received at the workshop and during the May 1 through 31 comment period were considered by DNREC. This report has been updated to address public comments by Mid-Atlantic Environmental Law Center (Sections 1.1, 2.0, 4.0, 4.2, 6.1, 6.4 and 6.5).
i
CONTENTS
Section Page
PREFACE...... i CONTENTS ...... ii FIGURES...... iii TABLES ...... iv
1 INTRODUCTION...... 1-1 1.1 303(d) LISTED WATERBODIES...... 1-1 1.2 DESIGNATED USES...... 1-3 1.3 APPLICABLE WATER QUALITY STANDARDS AND NUTRIENT GUIDELINES ...... 1-3
2 MODELING FRAMEWORKS...... 2-1 2.1 MODEL SEGMENTATION/DELINEATION ...... 2-2
3 WATERSHED CHARACTERISTICS ...... 3-1 3.1 LANDUSE ...... 3-1 3.2 POINT SOURCES ...... 3-1
4 WATERSHED MONITORING...... 4-1 4.1 OVERALL WATER QUALITY ASSESSMENT...... 4-2 4.2 SOURCES OF POLLUTION...... 4-2
5 SCOPE AND OBJECTIVES OF THE TMDL ANALYSIS...... 5-1 5.1 TOTAL MAXIMUM DAILY LOADS AND THEIR ALLOCATIONS ...... 5-1 5.2 TMDL ENDPOINTS ...... 5-2 5.3 TMDL MODEL OUTPUT PRESENTATION ...... 5-3 5.4 INTERPRETATION OF RESULTS...... 5-4
6 PROPOSED TMDL LOAD REDUCTION...... 6-1 6.1 CONSIDERATION OF THE IMPACT OF BACKGROUND POLLUTANTS ...... 6-1 6.2 CONSIDERATION OF CRITICAL ENVIRONMENTAL CONDITIONS ...... 6-2 6.3 CONSIDERATION OF SEASONAL VARIATIONS...... 6-2 6.4 CONSIDERATION OF MARGIN OF SAFETY...... 6-5 6.5 CONSIDERATION OF MODEL CAPABILITIES AND LIMITATIONS ...... 6-5 6.6 TMDL IMPLEMENTATION / PUBLIC PARTICIPATION ...... 6-7
7 REFERENCES ...... 7-1
APPENDIX 1 – EXISTING & TMDL MODEL OUTPUT (FRESHWATER) APPENDIX 2 – EXISTING & TMDL MODEL OUTPUT (MARINE) APPENDIX 3 – LEIPSIC RIVER BASELINE LOADINGS APPENDIX 4 – LEIPSIC RIVER LSPC INPUTS
ii
FIGURES
Figure Page
Figure 1. LSPC Model Segmentation Leipsic River Watershed...... 2-4 Figure 2. ECOMSED Grid...... 2-5 Figure 3. RCA Model Segmentation Leipsic River Watershed...... 2-6 Figure 4. Subwatershed Groupings Leipsic River Watershed...... 6-4
iii TABLES
Table Page
Table 1. Leipsic River Watershed TMDL Segments ...... 1-2 Table 2. Summary of Land Use in the Leipsic River Watershed...... 3-1 Table 3. Proposed TMDLs For The Leipsic River Watershed...... 6-2 Table 4. Leipsic River NPS LA by Land Use and Watershed Group...... 6-3
iv 1-1
SECTION 1
1 INTRODUCTION
As required by the Federal Clean Water Act, the Delaware Department of Natural Resources and Environmental Control (DNREC) is responsible for implementing water quality monitoring and assessment activities in the State and also for establishing Total Maximum Daily Loads (TMDLs) on impaired State surface waters as indicated on the State’s 303(d) List. In addition, the State of Delaware is under a court-approved Consent Decree (C.A. No. 96-591, D. Del 1996) that requires completion of TMDLs for certain impaired State waters by 2006. In order to complete these TMDLs, DNREC has contracted with the environmental modeling firm (HydroQual, Inc.) to develop mathematical models of the Leipsic River watershed to assist in developing the TMDLs. These mathematical models include a landside watershed model to calculate nonpoint source (NPS) runoff and quality, a hydrodynamic model to calculate the movement of water in the tidal reaches of the Leipsic River (downstream of Garrison’s Lake), and a water quality model that is coupled to the hydrodynamic model to calculate water quality in the tidal reaches of the river. As part of the Leipsic River watershed model development, data compilation and analyses were completed in addition to model development, calibration and validation. The data compilation/analysis and model development is presented in the following technical memorandum and report:
• Leipsic River Watershed TMDL Development, Data Analysis Technical Memorandum (HydroQual, 2005); and • Leipsic River Watershed TMDL Model Development (HydroQual, 2006). A summary of some of the data and modeling information related to the Leipsic River TMDL is presented below but detailed information relating to data and modeling are contained in these two references.
1.1 303(D) LISTED WATERBODIES The waterbodies listed on the State of Delaware’s 1998, 2002, 2004, and 2006 Draft 303(d) Lists in the Leipsic River Watershed are presented in Table 1. There are a total of 7 listed water segments: 1 tidal segment of the Leipsic River; 4 freshwater stream segments; and 2 freshwater lakes or ponds. These segments are listed for nutrients, DO and bacteria with the most probable source of pollutants identified as NPS. The TMDL development in the Leipsic River watershed was completed to address these water quality impairments and present TMDLs that are aimed at improving water quality in the listed segments.
1-2
Table 1. Leipsic River Watershed TMDL Segments
Size Probable Waterbody ID Segment Description Parameters Affected Source
Lower Leipsic From dam at Garrisons Lake to mouth at DE160-001 13.6 miles Bacteria, DO, nutrients NPS River Delaware River
Upper Leipsic From headwaters to Garrisons Lake, DE160-002 5.8 miles Bacteria, DO, nutrients NPS River excluding Masseys Mill Pond From the start of the third order stream Upper Leipsic DE160-002 2.7 miles on Pinks Branch to the confluence with DO NPS River Garrison Lake Dyke Branch from headwaters to DE160-004 Dyke Branch 4.39 miles Bacteria, DO, nutrients NPS confluence with Leipsic River
Muddy Branch from headwaters to DE160-004 Muddy Branch 5.59 miles Bacteria, DO, nutrients NPS confluence with Leipsic River
DE160-L01 Garrisons Lake 85.9 acres Lake south of Smyrna Bacteria, DO, nutrients NPS
Masseys Mill DE160-L02 30.0 acres Pond South of Clayton Bacteria, DO, nutrients NPS Pond
1-3
1.2 DESIGNATED USES According to the “State of Delaware Surface Water Quality Standards (Amended July 11, 2004)”, the designated uses that must be maintained and protected through the application of appropriate criteria are uses for: industrial water supply; primary contact recreation; secondary contact recreation; fish, aquatic life and wildlife including shellfish propagation; and agricultural water supply in freshwater segments only. These designated uses are applicable to the Leipsic River and are achieved and maintained through the application of water quality standards and criteria as outlined in the next section.
1.3 APPLICABLE WATER QUALITY STANDARDS AND NUTRIENT GUIDELINES According to the “State of Delaware Surface Water Quality Standards (Amended July 11, 2004)”, water quality standards (WQS) for dissolved oxygen (DO) and enterococcus exist. The DO WQSs in freshwater are a daily average of not less than 5.5 mg/L (minimum of 4 mg/L) and in marine waters are a daily average of not less than 5 mg/L (minimum of 4 mg/L). The enterococcus WQS consists of two parts, a single sample value not to exceed and a monthly geometric mean. For primary contact recreation in freshwater, the enterococcus WQS is a single sample value of 185 colonies/100mL (col/100mL) and a monthly geometric mean of 100 col/100mL. For primary contact recreation in marine waters, the enterococcus WQS is single sample value of 104 col/100mL and a monthly geometric mean of 35 col/100mL. For nutrients, some site-specific or basin-specific standards exist but acceptable nutrient levels are determined based on their ultimate effect on DO or algal levels through nutrient-algal-DO relationships (eutrophication) and/or threshold levels. The nutrient standards are currently in narrative form for controlling nutrient overenrichment and are stated as: "Nutrient overenrichment is recognized as a significant problem in some surface waters of the State. It shall be the policy of this Department to minimize nutrient input to surface waters from point sources and human induced nonpoint sources. The types of, and need for, nutrient controls shall be established on a site-specific basis. For lakes and ponds, controls shall be designed to eliminate over enrichment." Although national numeric nutrient criteria have not been established in Delaware, DNREC has used threshold levels of 3.0 mg/L for total nitrogen (TN) and 0.2 mg/L for total phosphorous (TP) for listing waterbodies on the State's 303(d) listings and 305(b) assessment reports and, therefore, will be used as the target nutrient levels for completing nutrient TMDLs in addition to considering nutrient endpoints such as DO and algal levels (chlorophyll-a). Nutrient related algal effects typically require sufficient time for impacts to be noticed (i.e., impacts are long term in nature rather than instantaneous), therefore, the nutrient targets will be assessed based on monthly average nutrient concentrations.
2-1
SECTION 2
2 MODELING FRAMEWORKS
The Leipsic River watershed model was developed to complete nutrient, DO and bacteria TMDLs in the watershed. The model framework is comprised of three components: a landside model, a hydrodynamic model and a water quality model. The landside model characterizes the hydrology and NPS loadings within the watershed. The hydrodynamic model simulates the tidal motion of water due to freshwater flow, density driven currents, and meteorology confined by a realistic representation of the systems bathymetry and also calculates salinity and temperature. The coupled water quality model calculates nutrient mediated algal growth and death, dissolved oxygen (DO), the various organic and inorganic forms of nitrogen, phosphorus, and carbon (BOD). In addition, bacteria (enterococcus) kinetics (die-off) are also modeled. The landside model used in the study is the Loading Simulation Program in C++ (LSPC). The LSPC model uses meteorological conditions (precipitation, evapotranspiration, air temperature, wind speed, dewpoint temperature, cloud cover and solar radiation) and land cover/use data to simulate flow, sediment transport, temperature variations, and water quality processes over the entire hydrologic cycle. Accumulation rates and limits used by LSPC as input parameters are tabulated by landuse in Appendix 4. The model results provide runoff flow and NPS loadings to the hydrodynamic and water quality models. The hydrodynamic model used in the study is the three-dimensional, time-dependent, estuarine and coastal circulation model Estuary and Coastal Ocean Model (ECOMSED), which has been successfully applied in numerous studies, such as the South Atlantic Bight (NY/NJ), Hudson- Raritan Estuary (NY/NJ), Long Island Sound (NY/CT), Delaware River, Bay and adjacent continental shelf (NJ/PA/MD/DE), Chesapeake Bay (MD/DE), Massachusetts Bay and Boston Harbor (MA), Tar-Pamlico Estuary (NC), and St. Andrew Bay (FL). The water quality model used in the study is a state-of-the-art eutrophication model Row Column Aesop (RCA) that is directly coupled with the hydrodynamic model, allowing computation of water quality within the tidal cycle. In addition, a sediment flux submodel is also included in the water quality model to allow calculation of sediment oxygen demand (SOD) and sediment nutrient fluxes in response to settled organic matter and its subsequent decay in the sediment. The coupled water quality/hydrodynamic model has been successfully applied in numerous studies including the Hudson-Raritan Estuary (NY/NJ), Long Island Sound (NY/CT), Chesapeake Bay (MD/DE), Massachusetts Bay and Boston Harbor (MA), Jamaica Bay (NY), Tar-Pamlico Estuary (NC), and the Upper Mississippi River (MN). The landside, hydrodynamic and water quality models were calibrated and validated with data collected by Delaware Department of Natural Resources and Environmental Control (DNREC), New Jersey Department of Environmental Protection (NJDEP)
2-2 and University of Deleware. These data include ADCP data in the lower estuary, temperature, salinity and water quality (nitrogen, phosphorus, organic carbon, DO, chlorophyll-a, bacteria) data in the tidal Leipsic River and non-tidal upstream areas of the watershed. The calibrated and validated landside, hydrodynamic and water quality models resulted in reasonable representation of both the complex mixing and circulation patterns observed in the study area and the observed nutrient, phytoplankton, organic carbon, DO and bacteria dynamics of the system. The segments on the State of Delaware’s 303(d) list were either modeled in the landside model or the tidal water quality model. Based on data availability, the year 2002 was chosen as the model calibration period. The calibrated landside, hydrodynamic and water quality models were then validated with data from the year 2003. The comparison of both the calibration and validation model results with available data shows that the calibrated models reasonably represent the hydrologic, hydrodynamic, and water quality processes present in the watershed. The linked landside, hydrodynamic and water quality models were developed to complete the TMDLs in the Leipsic River watershed. Calibration and validation of the models provide a consistent set of model coefficients that realistically represents the datasets in both modeling time periods. The calibrated and validated models are now used to develop TMDLs and load allocations for nutrients, DO and bacteria. Complete details of the models, development and application are presented in the report “Leipsic River Watershed TMDL Model Development” (HydroQual, 2006).
2.1 MODEL SEGMENTATION/DELINEATION The LSPC model was delineated into 24 sub-watersheds in the Leipsic River watershed (Figure 1). Preliminary model segment delineation was performed based on Digital Elevation Model (DEM) data developed by the University of Delaware and the river reach file information from DNREC. Further refinement of the model segmentation was then completed by inclusion of the location of the water quality stations and flow gages and re-assessment of the DEM and river reach file information. One hydrodynamic model was completed for the Blackbird Creek, Smyrna River, Leipsic River and Little River watersheds and portions of the Delaware River/Bay upstream and downstream from these watersheds. A marsh area north of the Smyrna River watershed and south of the Blackbird Creek watershed (approximately 9.5 mi2) drains directly into the Delaware River and was excluded from the watershed, hydrodynamic and water quality models. Segmentation of the hydrodynamic model resulted in a 41x72x5 model grid that consisted of 1,114 water segments in the horizontal plane and 5 equal water segments in the vertical dimension, for a total of 5,570 water segments. Figure 2 presents the model segmentation of the hydrodynamic model. For the Leipsic River watershed water quality model, water segments representing the Blackbird Creek, Smyrna River and Little River watersheds were masked out of the above hydrodynamic grid to create a water quality model grid with only 328 water segments in the horizontal plane and 1,640 total with
2-3 inclusion of the vertical dimension. The Leipsic River watershed water quality model grid is shown in Figure 3. The hydrodynamic and water quality model segments were developed in the Leipsic River and extended into Delaware River/Bay across the width from the lower river estuary and 5 miles in the upstream/downstream direction. The extension of the model grid into the bay is aimed at minimizing the bay boundary condition effects on the internal model calculations. Bathymetry data for the study area were obtained from NOAA GEODAS CDs (NOAA, 1998) and also DNREC ADCP data. Figure 3 presents the ADCP stations in the Leipsic River. The bathymetry assigned for the segmentation at the most upstream reaches of the tidal river were determined based on the tidal range and a minimum water depth was assigned to avoid main channel segments from drying out at low tide. In addition, the hydrodynamic model represents the wetting and drying of marsh areas in the river. These areas were determined from USGS topographic maps and delineated marsh areas. This was completed to better represent tidal transport in the river. As the tide rises and falls, water flows into and out of the marsh areas. When the tide is low, some of the marsh area segments dry up, or contain no water, and are considered computationally inactive. When the tide rises, water fills these segments and computation continues as normal. Marsh loads are only input into the marsh segments when they are considered wet, or computationally active. Figure 3 shows the model segments that are available for wetting and drying and the delineated marsh areas.
Land Use DNREC Water Quality Station 303d Stream Urban or Built-up Land Stream Agriculture Shoreline Pasture/Rangeland Watershed Boundary Forest LSPC Model Deliniation Wetlands Water Other 202211
SMYRNA RIVER WATERSHED
1
LEIPSIC RIVER WATERSHED 3
5 11 29 10 202161 9 202141 202031 4 202131 202011 13 22 12 202201 202021 6 202181 20 16 202191 19 23 202151 15 14 202171 28 21 27 30 31
25 26
LITTLE RIVER WATERSHED
Figure 1: LSPC Model Segmentation 1200 MacArthur Blvd. Leipsic River Watershed 1 0.5 0 1 2 Mahwah, New Jersey 07430 (201) 529-5151 f: (201) 529-5728 Miles 91005 DNREC Water Quality Stations DRBC Water Quality Stations NJDEP Water Quality Stations Datasonde Water Quality Stations ADCP Stations
91002 303d Stream Stream Shoreline ECOMSED Model Grid Waterbody Watershed Boundary
48 BLACKBIRD CREEK WATERSHED 110091 110041
110031
91017
201171 13 201121 4 201041 110101 10
SMYRNA RIVER 11 WATERSHED 5700003766 202211 201201 201191 201051 20 201031 91020 201181 635600002B 201161 201141 5700003653 15 201021 LEIPSIC RIVER 570000323A 201151 WATERSHED 5700003255 29 202181 202161 202201 202141 26 34 202031 202131 202191 35 202041 570000299B 41 202151 202171
91023
204041 204031 204021 61 204081 5700002420 56 60 LITTLE RIVER WATERSHED 570000220B 204011
91028 570000193G
Figure 2: ECOMSED Grid 1200 MacArthur Blvd. Mahwah, New Jersey 07430 2 1 0 2 (201) 529-5151 f: (201) 529-5728 Miles DNREC Water Quality Stations DRBC Water Quality Stations NJDEP Water Quality Stations Datasonde Water Quality Stations Wet/Dry Segment ADCP Stations Main Channel Segment 303d Stream Stream Shoreline RCA Model Grid ECOMSED Model Grid 91017 Waterbody Watershed Boundary Delineated Marsh Areas
5700003766
SMYRNA RIVER 202211 WATERSHED
91020 635600002B 5700003653 570000323A
LEIPSIC RIVER WATERSHED 5700003255 202161 2 29 202031 5 35 202141 8 26 4 3 1 34 7 6 202151 202181 202131 570000299B
202171 91023
5700002420 LITTLE RIVER WATERSHED
Figure 3: RCA Model Segmentation 1200 MacArthur Blvd. Leipsic River Watershed 2 1 0 2 Mahwah, New Jersey 07430 (201) 529-5151 f: (201) 529-5728 Miles 3-1
SECTION 3
3 WATERSHED CHARACTERISTICS
3.1 LANDUSE Land use information for the year 2002 was obtained from DNREC and is presented in Table 2 and Figure 1. The Leipsic River watershed is approximately 27,138 acres (105 mi2) and is primarily non-urban (93.5%) with approximately 40% agricultural land use.
3.2 POINT SOURCES In the Leipsic River watershed, there are no existing point sources (PS). Septic bacteria and nutrient loads were assigned in the model based on septic distribution in the watershed as provided by DNREC. An animal bacteria load was assigned similarly based on animal distribution in the watershed as provided by DNREC and guided by the USEPA Bacterial Indicator Tool (USEPA, 2000). Animal nutrient sources were subsumed in the overall land use unit loading values.
Table 2. Summary of Land Use in the Leipsic River Watershed
Land Use Area (ha) % Total Area Agriculture 10,945 40.3 Forest 1,729 6.4 Pasture/Rangeland 81 0.3 Urban/Built-up Land 1,773 6.5 Water 2,010 7.4 Wetland 10,441 38.5 Others 159 0.6 Total 27,138 100.0
4-1
SECTION 4
4 WATERSHED MONITORING
Monitoring in the Leipsic River watershed has been on-going since the mid-1970s and is aimed at providing information to assess water quality in the watershed but also to assist in the development of TMDL models. The water quality and hydrologic data collected were sufficient to support development and calibration/validation of watershed, hydrodynamic and water quality models for the Leipsic River, tributaries and ponds to establish TMDLs for nutrients, DO and bacteria. The data provided by the DNREC included DNREC water quality monitoring data, land use information, cross-sectional data, datasonde data, Acoustic Doppler Current Profile (ADCP) Data and National Pollutant Discharge Elimination System (NPDES) point source information. The land use data were used to generate inputs for the landside model along with meteorological conditions. The cross-sectional data, salinity, temperature, together with meteorological conditions were used to set up and calibrate/validate the hydrodynamic model. The water quality data were used to develop inputs and calibrate/validate the eutrophication/water quality model. Figure 1 presents an overview of the watershed, USGS flow gages, dams and water quality stations. The following data were available:
• DNREC Water Quality Monitoring Data – This set of data includes temperature, salinity, pH, total suspended solids (TSS), turbidity, secchi depth, nutrients (nitrogen and phosphorus), DO, carbonaceous biochemical oxygen demand (CBOD), total organic carbon (TOC), dissolved organic carbon (DOC), chlorophyll-a (chla), and enterococcus. There are 12 stations in the Leipsic River watershed as shown in Figure 1. The available data span from 1994 to 2003, but the majority of the data are between 2002 and 2003. All three models (landside, hydrodynamic and water quality) were calibrated with these data.
• Datasonde Data – The datasonde data contain tidal salinity, temperature, dissolved oxygen, pH and depth measurements collected between April 2002 and November 2003 for 3 sites in the Leipsic River. The datasonde locations are presented in Figure 3. Temperature and salinity data were used to calibrate/validate the hydrodynamic model. Dissolved oxygen data were used to calibrate/validate the water quality model.
• NPDES Point Source Data – The PS database contains information on effluent limits and discharge monitoring data for NPDES permitted PSs located in the State of Delaware. There are no point sources located in the Leipsic River Watershed.
4-2
• Cross-Sectional Data – The cross-sectional data include cross-section width, depth, and velocity for a number of stations in the Leipsic River watershed as presented in Figure 1. Although stations are shown along the main stem of the Leipsic River, no actual data are available at these stations. Data are available for stations tributary to the main stem of the river. River geometry was developed for the landside and hydrodynamic models using these data.
• ADCP Data – The ADCP data contain tidal velocity measurements conducted on October 5, 2005 for 8 sites in the estuary portion of the Leipsic River. The monitoring locations are presented on Figure 3. These data were used to help define river geometry and aided in calibration of the velocities and water depths in the hydrodynamic model.
• Flow Data – No USGS flow data were available for the Leipsic River watershed. The watershed model inputs were based on work completed in the Blackbird Creek and St. Jones River watersheds where USGS gages were available for calibration/validation of the landside model.
4.1 OVERALL WATER QUALITY ASSESSMENT In general, the water quality data analysis in the Leipsic River watershed indicates that the watershed experiences DO levels less than the State minimum WQS of 4 mg/L with high chlorophyll-a levels at many stations throughout the watershed. Potential oxygen demands include sediment oxygen demand (SOD), BOD oxidation, ammonia nitrification and/or algal respiration. These oxygen demands can originate from point and nonpoint sources but also potentially from wetland/marsh loading of organic material. The data indicate sufficient nutrient concentrations at most of the stations to support algal growth. Bacteria concentrations are also elevated at some stations (with maximum enterococcus levels above 2,000 #/100mL). Potential bacteria sources include storm water runoff and NPS derived bacterial inputs.
4.2 SOURCES OF POLLUTION Nonpoint source pollution can be defined as pollution that occurs over large areas as a result of common practices and landuses. Unlike a point source that deposits pollution into a water body at a specific location, nonpoint sources will affect a waterbody at indefinite locations, such as ground water seepage or agricultural runoff along a given stream length. In order to quantify nonpoint sources in the Leipsic River watershed, land areas were classified according to landuse and pollutant build-up and wash-off coefficients and groundwater concentrations. The landuse distribution in the Leipsic River watershed was generalized into the groups shown in Table 2: agriculture, forest, pasture/rangeland, urban/built-up, wetlands and others. Each of these landuses has different
4-3 possible sources of pollution that are deposited directly or indirectly to the water system. The “other” landuse includes transitional construction and inland natural sandy areas. Forested areas account for a little more than 6 percent of the watershed. The types of forest are deciduous, mixed and evergreen. Nutrients and bacteria from wild animals and organic material from plants are common sources of nonpoint pollution. Wetland areas account for more than 38 percent of the watershed area and are home to many species of plants and wildlife that produce organic, nutrient and bacteria wastes. Approximately 40 percent of the Leipsic River watershed was classified as agriculture, including cropland, farm related buildings, idle fields, and orchard and nursery landuses. Possible nonpoint sources of pollution from these areas include bacteria and nutrients from animal feed lots, organic material from plants, nutrients from industrial fertilizers, and particulate and dissolved nutrients in runoff. Pasture/rangeland comprises less than 1 percent of the watershed and includes pasture and herbaceous, brush and mixed rangelands. Nutrients and bacteria from animal grazing or production are common sources of nonpoint pollution. Urban or built-up landuses often increase nonpoint pollution due to decreased perviousness and increased human development. The urban landuse contains roads, salvage yards, mixed urban, professional retail, single family dwellings, utilities and warehouses. Among the causes of pollution from urban landuses are nutrients and bacteria in runoff from impervious surfaces, nutrients and bacteria from septic systems, nutrients from residential fertilizers, industrial wastes and domestic pet wastes. Approximately 7 percent of the Leipsic River watershed is urban or built-up. Based on the land use data, the Leipsic River watershed is primarily non-urban (93.5%). There are no active NPDES permitted PSs or MS4 permitted urbanized areas in the watershed. Therefore, NPSs are the dominant source of pollution in the watershed.
5-1
SECTION 5
5 SCOPE AND OBJECTIVES OF THE TMDL ANALYSIS
DNREC has proposed TMDLs for nitrogen, phosphorous, DO and bacteria for the Leipsic River watershed. The proposed TMDLs are the result of various load reduction analyses, which were conducted using the Leipsic River Watershed Model as a predictive tool. The proposed TMDL is designed such that, when implemented, all segments of the Leipsic River system will achieve applicable water quality standards and targets for TN, TP, DO and bacteria. Monitoring in the watershed should continue to assess the impact of load reductions and to determine the associated water quality improvements. In this manner, an adaptive management approach can be followed in the watershed. In order to complete these TMDLs, mathematical models of the Leipsic River watershed were developed. These mathematical models include a landside watershed model to calculate nonpoint source (NPS) runoff and quality, a hydrodynamic model to calculate the movement of water in the tidal reaches of the Leipsic River (downstream of Garrison’s Lake), and a water quality model that is coupled to the hydrodynamic model to calculate water quality in the tidal reaches of the river. As part of the Leipsic River watershed model development, data compilation and analyses were completed in addition to model development, calibration and validation. The data compilation/analysis and model development is presented in the following technical memorandum and report:
• Leipsic River Watershed TMDL Development, Data Analysis Technical Memorandum (HydroQual, 2005); and • Leipsic River Watershed TMDL Model Development (HydroQual, 2006). In addition, baseline NPS loadings were developed (Figure 4 and Appendix 3) based on the calibration/validation period (2002-2003).
5.1 TOTAL MAXIMUM DAILY LOADS AND THEIR ALLOCATIONS The calibrated and validated Leipsic River models were used to determine TMDLs for the watershed. This effort involved completing various model load reduction scenarios to ultimately arrive at a load reduction scenario that meets water quality standards or targets. The following procedure was used to develop the load reduction scenarios, wasteload allocations (WLA) and load allocations (LA). An implicit margin of safety (MOS) will be used for the TMDL due to conservative assumptions used in the modeling. In order to address NPS loadings within the watershed, various load reduction scenarios were completed for 20%, 40%, 60% and 80% NPS load reductions. The results of these NPS load
5-2 reductions scenarios were used to establish the proposed NPS reduction goal for the Leipsic River TMDL. In these analyses, meeting the water quality standards and/or targets reflect achieving the designated uses.
5.2 TMDL ENDPOINTS For nutrients, the water quality targets were interpreted to represent monthly average nutrient targets of 3 mg/L TN and 0.2 mg/L TP. These targets were applied in both the freshwater and tidal reaches of the watershed. The monthly average approach was chosen because nutrient effects on algae are not immediate, that is sufficient time is required for the consumption of nutrients by algae in increasing their biomass. Given the nature of the streams, ponds and tidal reaches in the Leipsic River watershed, a monthly time period was considered suitable for assessing nutrient related algal impacts for TMDL development. For bacteria (enterococcus), the water quality standard is two-tiered. The Delaware standards are expressed as a single sample maximum and geometric mean without reference to a time period. Typically, bacteria standards are written in terms of a monthly time period and, therefore, the bacteria standards were applied on a monthly basis for TMDL development. In the freshwater reaches the enterococcus geometric mean standard is 100 #/100mL and in the marine reaches the geometric mean standard is 35 #/100mL. Compliance with these standards was based on the calculated maximum 30-day moving geometric mean that occurs in a calendar month. For DO, the water quality standard is also two-tiered to represent a daily average and daily minimum value. In the freshwater reaches the DO daily average value is 5.5 mg/L with a minimum of 4.0 mg/L. In the marine reaches the DO daily average value is 5.0 mg/L with a minimum of 4.0 mg/L. In the upstream freshwater reaches a steady-state, low-flow (7Q10) DO balance calculation was completed to determine the allowable loads that meet the daily average DO standard of 5.5 mg/L. This approach used the Streeter-Phelps DO deficit method to calculate DO as a function of oxygen demands (CBOD/NBOD from nonpoint sources, SOD) and the oxygen source from atmospheric reaeration. The approach used upstream geometry relationships (depth, velocity, width as a function of flow) to represent stream geometry at different flow rates. In addition, total flow calculated by LSPC at the end of a river reach was uniformly distributed along the length of the o tributary under consideration. A CBOD and NH3 decay rate of 2/day at 20 C was used along with a SOD of 1 g/m2/d at 20oC. Atmospheric reaeration at 20oC was calculated using the Tsivoglou
equation (Ka = CUS, where C is a constant that depends on flow, U us the velocity and S is the slope). All of these rates were temperature corrected to a summer maximum temperature of 30oC based on available data. An initial DO deficit of 0-2 mg/L (depending on stream reach) and
TBODu of 5 mg/L was assigned at the upstream end of the reach analyzed.
In order to test the approach against observed data, average NPS BOD and NH3 loads during the summer months of June through October (2002 and 2003) were obtained from the
5-3 calibrated LSPC model for the reach under consideration. The average stream flow during this period was also used to represent the average stream conditions for calculating stream geometry. The resulting DO calculation is presented in the top panel of the spatial DO figures in Appendix 1 along with the observed DO data. In general, the DO modeling approach reproduces the lower DO levels observed in Upper (non-tidal) Leipsic River, Dyke Branch, Muddy Branch, Garrisons Lake and Masseys Mill Pond. Since the stream flows during the summer of 2002 were at or below 7Q10 low flow conditions, a low stream flow of 0.5 cfs was used to assess whether the NPS load reductions improved DO levels to meet the standard of 5.5 mg/L. This was accomplished reducing the headwaters TBODu and stream SOD by 40%, assigning no upstream DO deficit and by removing the NPS TBODu load since at 7Q10 low flow conditions when runoff does not occur or is minimal. In other coastal Delaware watersheds, it was noted that many of the observed low DO values are reported as being collected in areas with no flow (stagnant, pooled reaches) or are located in headwater areas of small streams that may be dominated by groundwater with low DO levels. Therefore, monitoring of DO in these freshwater reaches should continue to either assess improvements due to the load reductions or to determine potential local sources of oxygen demand. In the tidal reaches of the watershed, the RCA model output was used to assess instream DO standards. In these downstream tidal reaches of the watershed, background oxygen demands such as sediment oxygen demand (SOD), bay water quality and marsh loadings can cause DO levels to be periodically naturally depressed. Therefore, assessment of compliance with the marine DO standard was based on monthly average model output.
5.3 TMDL MODEL OUTPUT PRESENTATION The model output for TN, TP, chlorophyll-a, DO and enterococcus is presented in a series of figures for comparing the load reduction scenarios to the water quality standards or targets. These model output figures are presented for the six (6) freshwater 303(d) listed segments (Appendix 1) and the one (1) tidal 303(d) listed segment (Appendix 2) at a number of monitoring locations. In the freshwater reaches, the steady-state, low-flow calculated DO as a function of distance is presented where a DO TMDL is required along with the associated DO deficit components. The current and TMDL loading conditions are also presented in this figure. For enterococcus, the current and TMDL model output are presented as probability distributions of the 30 day geometric mean. Probability distributions are useful for presenting the mean and variation of a data set, and also provide a means for determining compliance (percent exceedance) from a given value (e.g., a water quality standard). The Delaware standards do not allow for a percent of samples exceeding the standard (e.g., 10%) and, therefore, the load reductions are aimed at maintaining the instream enterococcus levels below the geometric mean standard at all times. For nutrients, monthly average concentrations are compared to the target levels of 3 mg/L for TN and 0.2 mg/L for TP. In the marine (tidal) reaches, monthly average DO is presented for both the current and TMDL loading conditions along with enterococcus. For enterococcus, the current and TMDL model
5-4 output are presented as probability distributions of the 30 day geometric mean in the same format as the freshwater reaches. For nutrients, monthly average concentrations are compared to the target levels of 3 mg/L for TN and 0.2 mg/L for TP. Chlorophyll-a is also presented as a monthly average for reference with a target concentration of 25 mg/L.
5.4 INTERPRETATION OF RESULTS The load reduction scenarios were designed to determine the impact of various NPS load reductions on instream water quality in the freshwater and tidal reaches of the watershed in order to guide in selection of the final TMDL load reduction scenario. Based on the four (4) nutrient load reduction scenarios completed (20%, 40%, 60% and 80% NPS load reductions), a final nutrient NPS load reduction of 40% was selected. Results from this final scenario are presented in Appendix 1 for the freshwater reaches and in Appendix 2 for the tidal reaches. The 40% nutrient NPS load reduction reduced all instream nutrient levels below their target levels and contributed to DO improvements in both the freshwater and tidal reaches through the associated carbon (BOD) and NH3 reductions. Although the existing nutrient targets were close to or less than the targets in the freshwater reaches, additional decreases were necessary to meet the nutrient targets in the downstream tidal reaches. NPS chlorophyll-a loads were also reduced by 20% and/or decreased to a maximum concentration of 8 µg/l to represent decreased chlorophyll-a concentrations as a result of decreased nutrient concentrations. In addition, the marsh loading of organic carbon and its contribution to SOD was reduced by 25% in the TMDL model runs that also contributed to DO improvements in the tidal reach of the river. This reduced organic carbon load represents potential SOD reductions that may occur as a result of NPS controls in the watershed. For bacteria, a 75% NPS load reduction is required to meet both the freshwater and marine geometric mean standards at all times. These NPS load reductions are greater than needed in the freshwater reaches but are necessary to attain the marine geometric mean standard in the tidal reach of the river. Therefore, the final load reductions recommended are a 40% NPS reduction of nutrients (including carbon or BOD) loads and a 75% NPS reduction of bacteria (enterococcus). These load reductions will allow the instream nutrient targets, DO and bacteria standards to be maintained in the watershed.
6-1
SECTION 6
6 PROPOSED TMDL LOAD REDUCTION
As stated, the proposed TMDL load reduction scenario is a 40% NPS reduction of nitrogen, phosphorus and carbon (BOD) and a 75% NPS reduction of enterococcus. These NPS load reductions are presented in Table 3 as the only load reductions in the Leipsic River watershed since no WLA (point sources or MS4 urban areas) are present. In both the freshwater and marine (tidal) reaches of the watershed, the nutrient targets, DO and bacteria standards are attained at these TMDL loading levels. Table 3 presents the TMDLs for nitrogen, phosphorus and enterococcus for the final proposed load reduction scenario and Table 4 presents a summary of the NPS loadings by sub- watershed and landuse. Figure 4 highlights the sub-watersheds used in Table 4. Appendix 3 presents a summary of the baseline (calibration/validation 2002/2003) loads for nitrogen, phosphorus and enterococcus. These load reduction scenarios are meant as a guide in improving water quality in the Leipsic River watershed and should be periodically revisited to determine whether they are still applicable. In addition, water quality monitoring should continue throughout the watershed to quantify the instream effects of the proposed load reductions and to monitor the calculated water quality improvement in the river.
6.1 CONSIDERATION OF THE IMPACT OF BACKGROUND POLLUTANTS The Leipsic River watershed TMDLs for nutrients, DO and bacteria were estimated using the results of calibrated/validated models (watershed, hydrodynamic and water quality). The models were developed using data collected in the field to represent model inputs and for calibration/validation of the models. The data collected in the field also reflected background pollutant conditions and Delaware Bay water quality in addition to tidal marsh loadings in the model. Therefore, the impact of background pollutants is accounted for in the model. The impact of pollutant sources varies significantly according to location in the watershed. The three major sources of nutrients are NPSs, the downstream connection to Delaware River/Bay and marsh contribution of organic matter. The Delaware River/Bay impacts DO and nutrient levels closer to the mouth of Leipsic River. Marshes have an influence on DO levels upstream of the river mouth and within the area of the tidal marshes. The upstream NPSs affect DO and nutrient levels minimally at the river mouth but show a generally increasing influence moving upstream (until dominating the nontidal portion of the creek). These three sources are the major causes of varying levels of background pollutants throughout the watershed and impact the model differently according to location.
6-2
Table 3. Proposed TMDLs For The Leipsic River Watershed Parameter WLA LA TMDL TN (lb/d) 0.0 559.36 559.36 TP (lb/d) 0.0 61.98 61.98 Enterococcus (#/d) 0.0 1.08E+11 1.08E+11
6.2 CONSIDERATION OF CRITICAL ENVIRONMENTAL CONDITIONS Low river flows during summer months coupled with high water temperatures represent critical conditions for nutrient related algal growth and DO assessments. High flow or wet weather conditions are also important for assessing NPSs. Since the Leipsic River watershed does not have a continuous flow gage, flow calibration for the Leipsic River watershed LSPC model was based on the calibrated and validated Blackbird Creek LSPC model where there was a USGS flow gage (#01483200). In the Blackbird Creek watershed, which borders the Smyrna River watershed to the north, the calibration year 2002 was a very dry year compared with the wetter year of 2003. The annual average flows at the Blackbird Creek USGS gage for these two years are 2.8 and 10.2 cfs, respectively. Likewise, in the St. Jones River watershed, which is located immediately south of the Little River and Leipsic River watersheds, a 7Q10 analysis was completed and indicates that the 7Q10 flow for the St. Jones River at Dover (USGS gage #01483700) is 0.7 cfs. The minimum average 7-day flow for year 2002 was 0.6 cfs at the St Jones River USGS gage, which is below the 7Q10 flow. Therefore, since the both the Blackbird Creek and St. Jones River watersheds suggest a dry year 2002 and a wet year 2003, the critical dry and wet weather conditions in the Leipsic River watershed are included in the analysis.
6.3 CONSIDERATION OF SEASONAL VARIATIONS Seasonal variations are considered in the Leipsic River models since the models were calibrated/validated in a time-variable mode for the years 2002-2003. This time period reflects flow and watershed conditions during all four seasons in both a dry and wet year. Therefore, seasonal variations have been considered for this analysis.
6-3
Table 4. Leipsic River NPS LA by Land Use and Watershed Group Parameter Urban Agriculture Pasture Forest Wetlands Total Lower Leipsic River Area (acres) 1,161 6,653 160 1,012 2,549 11,535 TN (lb/d) 74.45 88.96 4.01 4.86 14.04 186.32 TP (lb/d) 8.60 5.48 0.27 0.71 6.65 21.71 Enterococcus (#/d) 3.01E+10 1.09E+08 2.70E+08 4.47E+06 0.00E+00 3.05E+10 Upper Leipsic River Area (acres) 1,435 7,366 141 1,096 1,052 11,091 TN (lb/d) 92.01 98.50 3.49 5.27 5.80 205.05 TP (lb/d) 10.63 6.07 0.23 0.77 2.74 20.45 Enterococcus (#/d) 3.72E+10 1.20E+08 2.48E+08 4.84E+06 0.00E+00 3.76E+10 Muddy Branch Area (acres) 676 2,011 84 434 1,120 4,325 TN (lb/d) 43.34 26.90 2.48 2.08 6.17 80.97 TP (lb/d) 5.00 1.66 0.16 0.30 2.92 10.05 Enterococcus (#/d) 1.75E+10 3.29E+07 2.94E+07 1.91E+06 0.00E+00 1.76E+10 Dyke Branch Area (acres) 866 1,953 25 401 550 3,794 TN (lb/d) 55.50 26.12 0.44 1.93 3.03 87.01 TP (lb/d) 6.41 1.61 0.03 0.28 1.43 9.77 Enterococcus (#/d) 2.25E+10 3.19E+07 9.60E+07 1.77E+06 0.00E+00 2.26E+10
Subwatershed Grouping BLACKBIRD CREEK LSPC Model Deliniation WATERSHED
SMYRNA RIVER WATERSHED
1
LEIPSIC RIVER WATERSHED 3
5 Lower Leipsic River 29 10 11 9 13 4 12 6 22 19 20 16 23 Upper Leipsic River 15 14 28 21 Dyke Branch 27 30 31
Muddy Branch 25 26
LITTLE RIVER WATERSHED
Figure 4: Subwatershed Groupings 1200 MacArthur Blvd. Leipsic River Watershed 1 0.5 0 1 2 Mahwah, New Jersey 07430 (201) 529-5151 f: (201) 529-5728 Miles 6-5
6.4 CONSIDERATION OF MARGIN OF SAFETY USEPAs technical guidance allows consideration for the margin of safety as implicit or explicit. The margin of safety can account for uncertainty about the relationships between pollutant loads and receiving water quality in addition to uncertainty in the analysis (USEPA, 2001). An implicit margin of safety is when conservative assumptions are contained in model development and TMDL establishment. An explicit margin of safety is a specified percentage of assimilative capacity that is kept unassigned to account for uncertainties, lack of sufficient data or future growth. An implicit margin of safety has been considered for the Leipsic River TMDL analysis. The Leipsic River bacteria, nutrient and DO models were constructed with several implicit, conservative assumptions built into the models. In addition, the models represented the complex watershed dynamics and tidal nature of the river as opposed to analyzing with a simple model framework not accounting for these complex processes that would include more uncertainty. As stated in the Protocol for Developing Pathogen TMDLs (USEPA, 2001), “trade-offs associated with using simpler approaches include a potential decrease in predictive accuracy and often an inability to predict water quality at fine geographic and time scales … and the advantages of more detailed approaches are presumably an increase in predictive accuracy and greater spatial and temporal resolution”. The Leipsic River models were also developed from a comprehensive water quality database that was collected over several years (as described in this TMDL Report, Data Memorandum and Modeling Report). This also reduces the uncertainty in the analysis based on a good understanding of water quality dynamics as determined from the available observed field data. Furthermore for the TMDL scenarios, the reductions were applied to the entire watershed to satisfy the applicable water quality standards or targets at the most critical location rather than to specific reaches upstream of the critical location (i.e., downstream impacts were considered). This results in an implicit margin of safety in upstream areas since load reductions are applied to meet the standards/targets at the critical downstream locations. It was also assumed that the load reductions required are to be achieved by solely altering practices within the Leipsic River watershed. In the nutrient model this means that the downstream Delaware River/Bay boundary condition loadings are not reduced due to upstream Delaware River controls in the States of Delaware, Pennsylvania, New York and New Jersey not to mention coastal water quality. Since there is intrusion of water from Delaware River/Bay into the river and water quality of Delaware River/Bay will undoubtedly improve in the future, this adds an additional level of conservatism to the analysis since the boundary conditions were not changed for the TMDL analysis. Finally, critical stream conditions were considered in the TMDL analysis. That is, low-flow and high temperature conditions were part of the period that controlled the establishment of the TMDL loads. These loads, although based on monthly average conditions, reflect the critical
6-6 conditions that occur within this period. Particularly for discrete sources, the combination of low- flow, high temperature and maximum permit loading conditions represent a rare occurrence and, therefore, provide an additional level of conservatism and implicit margin of safety. For nonpoint sources, critical conditions are more driven by high-flow runoff events and these conditions are also represented in this TMDL analysis. Also, the BOD oxidation and SOD rates used in the freshwater reaches of the watershed for the DO assessment are on the high side of typical ranges and, therefore, also provide a level of conservatism and implicit margin of safety to the analysis. Overall, the implicit margin of safety chosen reflects the complex modeling developed for the TMDL analysis, comprehensive database available for model development, conservative modeling assumptions chosen and the overall objective of DNREC to implement TMDLs in a phased, adaptive implementation strategy. The use of an implicit margin of safety allows water quality improvements to be realized within the adaptive management framework while not imposing unnecessary source reduction costs on local stakeholders until real world water quality improvements can be better correlated to economically feasible source controls.
6.5 CONSIDERATION OF MODEL CAPABILITIES AND LIMITATIONS The Leipsic River watershed model is a valuable tool for the assessment and prediction of water quality parameters (including dissolved oxygen, enterococcus and nutrients) in the tidal and nontidal portions of the river. However, just like any model, the Leipsic River watershed model has limitations to go along with its capabilities. In the upstream nontidal reaches, the LSPC model has the ability to calculate instream concentrations at selected points in the river near water quality monitoring stations, lake inflows and outflows, confluences of reaches and other strategically selected locations. The driving functions for the model are the accumulation of pollutants on landuses and the delivery of pollutants to reaches through overland and groundwater flow. Currently, instream processes in LSPC are limited to deposition and first order decay. LSPC cannot calculate instream eutrophication or exchanges between the water column and sediment bed. Moreover, LSPC is a lumped parameter and landuse generalized model that is calibrated for whole watershed analyses and, therefore, LSPC’s loading functions should not be used to assess the effects of a specific site on downstream water quality without further research and verification of accumulation rates and runoff concentrations at the site. For the tidal reaches and estuaries of the Leipsic River watershed, the coupled, three dimensional ECOMSED (hydrodynamic) and RCA (eutrophication, sediment flux and bacteria) models account for the factors that influence water quality in a tidal system. Given the increased complexity of a tidal water body, the ECOMSED and RCA models are well suited to simulate flow and water quality because of their capabilities. It should be noted that the coupled model is loaded with flows and pollutant loads from the LSPC model and is, therefore, influenced by the same factors that limit LSPC. ECOMSED tracks flow and transport according to freshwater flow, density
6-7 driven currents, wind driven currents and other meteorological influences and can calculate flow, velocity, salinity and temperature at any three dimensional point in the tidal water body. The RCA eutrophication model can calculate dissolved oxygen, nutrients, carbon and chlorophyll-a concentrations at any three dimensional point in the water body based on sediment interactions, upstream sources of pollution, tidal flow and chemical interactions. The model also incorporates a net flux of nutrients and carbon (not seasonally varied) from tidal marshes. That is, nutrient and carbon uptake and export from wetlands was not considered in the marsh load but rather represented as an annual average net flux to the river. The RCA bacteria model contains the same transport and loading mechanisms as the eutrophication model along with a first order die-off algorithm to allow for computation of enterococcus at any three dimensional point in the tidal Leipsic River watershed. The bacteria model does not account for sediment fluxes or marsh loads to the water body. In general, the influence of nonpoint sources, point sources and boundary conditions from Delaware Bay/River on the water quality in the tidal water bodies of the Leipsic River can be assessed using the RCA eutrophication and bacteria models.
6.6 TMDL IMPLEMENTATION / PUBLIC PARTICIPATION DNREC will implement the requirements of this TMDL through development of a Pollution Control Strategy. As with all Pollution Control Strategies, DNREC will engage stakeholders through extensive public education and review process. The draft Proposed TMDLs for the Leipsic River watershed were reviewed during a public workshop held on 11 May, 2006. All comments received at the workshop and during the May 1 through 31 comment period were considered by DNREC. This report has been updated to address public comments by Mid-Atlantic Environmental Law Center (Sections 1.1, 2.0, 4.0, 4.2, 6.1, 6.4 and 6.5). Considering these opportunities, it can be concluded there has been adequate opportunity for public participation.
7-1
SECTION 7
7 REFERENCES
HydroQual, Inc., 2005. Leipsic River Watershed TMDL Development, Data Analysis Technical Memorandum (2005). Submitted to the Delaware Department of Natural Resources and Environmental Control. HydroQual, Inc., 2006. Leipsic River Watershed TMDL Model Development (March, 2006). Submitted to the Delaware Department of Natural Resources and Environmental Control. HydroQual, Inc., 2006. St. Jones River Watershed Proposed TMDLs (March, 2006). Submitted to the Delaware Department of Natural Resources and Environmental Control. USEPA Bacteria Indicator Tool, 2000. USEPA, 2001. Protocol for Developing Pathogen TMDLs, First Edition. USEPA Office of Water. EPA 841-R-00-002, January 2001.
APPENDIX 1 EXISTING & TMDL MODEL OUTPUT (FRESHWATER)
Existing Conditions - Upper Leipsic River 10 5
8 4 D O
D
) 6 3 e L / f i g c i m t (
( m O g D
4 2 / L )
2 DO (mg/L) DO Data (1997-2004) 1 Deficit due to Initial Do (mg/L) Deficit due to TBODu (mg/L) Deficit due to SOD (mg/L) Deficit due to distributed TBODu (mg/L) Total Deficit (mg/L) 0 0 0 1 2 3 4 5 6 Distance (miles)
TMDL Conditions - Upper Leipsic River 10 5 DO (mg/L) Deficit due to Initial Do (mg/L) Deficit due to TBODu (mg/L) Deficit due to SOD (mg/L) Deficit due to distributed TBODu (mg/L) Total Deficit (mg/L) 8 4 D O
D
) 6 3 e L / f i g c i m t (
( m O g D
4 2 / L )
2 1
0 0 0 1 2 3 4 5 6 Distance (miles)
Figure A1. Upper Leipsic River
A-1 Existing Conditions - Dyke Branch 10 5
DO (mg/L) DO Data (1997-2004) Deficit due to Initial Do (mg/L) Deficit due to TBODu (mg/L) Deficit due to SOD (mg/L) Deficit due to distributed TBODu (mg/L) 8 4 Total Deficit (mg/L) D O
D
) 6 3 e L / f i g c i m t (
( m O g D
4 2 / L )
2 1
0 0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 Distance (miles)
TMDL Conditions - Dyke Branch 10 5 DO (mg/L) Deficit due to Initial Do (mg/L) Deficit due to TBODu (mg/L) Deficit due to SOD (mg/L) Deficit due to distributed TBODu (mg/L) Total Deficit (mg/L) 8 4 D O
D
) 6 3 e L / f i g c i m t (
( m O g D
4 2 / L )
2 1
0 0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 Distance (miles)
Figure A2. Dyke Branch
A-2 Existing Conditions - Muddy Branch 10 5
DO (mg/L) DO Data (2002-2004) Deficit due to Initial Do (mg/L) Deficit due to TBODu (mg/L) Deficit due to SOD (mg/L) Deficit due to distributed TBODu (mg/L) 8 4 Total Deficit (mg/L) D O
D
) 6 3 e L / f i g c i m t (
( m O g D
4 2 / L )
2 1
0 0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 Distance (miles)
TMDL Conditions - Muddy Branch 10 5 DO (mg/L) Deficit due to Initial Do (mg/L) Deficit due to TBODu (mg/L) Deficit due to SOD (mg/L) Deficit due to distributed TBODu (mg/L) Total Deficit (mg/L) 8 4 D O
D
) 6 3 e L / f i g c i m t (
( m O g D
4 2 / L )
2 1
0 0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 Distance (miles)
Figure A3. Muddy Branch
A-3 Open Bar - Calibration/Validation, Filled Bar - TMDL 5
4
3
2 TN (mg/L)
1
0 J F M A M J J A S O N D
Open Bar - Calibration/Validation, Filled Bar - TMDL 0.50
0.40
0.30
0.20 TP (mg/L)
0.10
0.00 J F M A M J J A S O N D
Leipsic River (Non-Tidal) - Upper Leipsic River (DE160-002) Figure A4. Nutrient TMDL Results (2002-2003) 40% NPS Reduction (Calibration and TMDL Run 15, LSPC Segment 9)
A-4 Open Bar - Calibration/Validation, Filled Bar - TMDL 5
4
3
2 TN (mg/L)
1
0 J F M A M J J A S O N D
Open Bar - Calibration/Validation, Filled Bar - TMDL 0.50
0.40
0.30
0.20 TP (mg/L)
0.10
0.00 J F M A M J J A S O N D
Leipsic River (Non-Tidal) - Masseys Mill Pond (DE160-L02) Figure A5. Nutrient TMDL Results (2002-2003) 40% NPS Reduction (Calibration and TMDL Run 15, LSPC Segment 12)
A-5 Open Bar - Calibration/Validation, Filled Bar - TMDL 5
4
3
2 TN (mg/L)
1
0 J F M A M J J A S O N D
Open Bar - Calibration/Validation, Filled Bar - TMDL 0.50
0.40
0.30
0.20 TP (mg/L)
0.10
0.00 J F M A M J J A S O N D
Leipsic River (Non-Tidal) - Muddy Branch (DE160-004) Figure A6. Nutrient TMDL Results (2002-2003) 40% NPS Reduction (Calibration and TMDL Run 15, LSPC Segment 23)
A-6 Open Bar - Calibration/Validation, Filled Bar - TMDL 5
4
3
2 TN (mg/L)
1
0 J F M A M J J A S O N D
Open Bar - Calibration/Validation, Filled Bar - TMDL 0.50
0.40
0.30
0.20 TP (mg/L)
0.10
0.00 J F M A M J J A S O N D
Leipsic River (Non-Tidal) - Garrisons Lake (DE160-L01) Figure A7. Nutrient TMDL Results (2002-2003) 40% NPS Reduction (Calibration and TMDL Run 15, LSPC Segment 29)
A-7 Open Bar - Calibration/Validation, Filled Bar - TMDL 5
4
3
2 TN (mg/L)
1
0 J F M A M J J A S O N D
Open Bar - Calibration/Validation, Filled Bar - TMDL 0.50
0.40
0.30
0.20 TP (mg/L)
0.10
0.00 J F M A M J J A S O N D
Leipsic River (Non-Tidal) - Dyke Branch (DE160-004) Figure A8. Nutrient TMDL Results (2002-2003) 40% NPS Reduction (Calibration and TMDL Run 15, LSPC Segment 30)
A-8 10000 Solid - Calibration/Validation Dashed - TMDL Results
1000
100 Geometric Mean Stnd
10 Enterococcus (#/100mL)
1 0.1 1 10 20 50 80 90 99 99.9 % Less than or Equal to
Leipsic River (Non-Tidal) - Upper Leipsic River (DE160-002) Figure A9. Enterococcus TMDL Results (2002-2003) 75% NPS Reduction (Calibration and TMDL Run 15, LSPC Segment 9)
A-9 10000 Solid - Calibration/Validation Dashed - TMDL Results
1000
100 Geometric Mean Stnd
10 Enterococcus (#/100mL)
1 0.1 1 10 20 50 80 90 99 99.9 % Less than or Equal to
Leipsic River (Non-Tidal) - Masseys Mill Pond (DE160-L02) Figure A10. Enterococcus TMDL Results (2002-2003) 75% NPS Reduction (Calibration and TMDL Run 15, LSPC Segment 12)
A-10 10000 Solid - Calibration/Validation Dashed - TMDL Results
1000
100 Geometric Mean Stnd
10 Enterococcus (#/100mL)
1 0.1 1 10 20 50 80 90 99 99.9 % Less than or Equal to
Leipsic River (Non-Tidal) - Muddy Branch (DE160-004) Figure A11. Enterococcus TMDL Results (2002-2003) 75% NPS Reduction (Calibration and TMDL Run 15, LSPC Segment 23)
A-11 10000 Solid - Calibration/Validation Dashed - TMDL Results
1000
100 Geometric Mean Stnd
10 Enterococcus (#/100mL)
1 0.1 1 10 20 50 80 90 99 99.9 % Less than or Equal to
Leipsic River (Non-Tidal) - Garrisons Lake (DE160-L01) Figure A12. Enterococcus TMDL Results (2002-2003) 75% NPS Reduction (Calibration and TMDL Run 15, LSPC Segment 29)
A-12 10000 Solid - Calibration/Validation Dashed - TMDL Results
1000
100 Geometric Mean Stnd
10 Enterococcus (#/100mL)
1 0.1 1 10 20 50 80 90 99 99.9 % Less than or Equal to
Leipsic River (Non-Tidal) - Dyke Branch (DE160-004) Figure A13. Enterococcus TMDL Results (2002-2003) 75% NPS Reduction (Calibration and TMDL Run 15, LSPC Segment 30)
A-13
APPENDIX 2 EXISTING & TMDL MODEL OUTPUT (MARINE)
Open Bar - Calibration/Validation, Filled Bar - TMDL 5
4
3
2 TN (mg/L)
1
0 J F M A M J J A S O N D
Open Bar - Calibration/Validation, Filled Bar - TMDL 0.50
0.40
0.30
0.20 TP (mg/L)
0.10
0.00 J F M A M J J A S O N D
Open Bar - Calibration/Validation, Filled Bar - TMDL 150
125
100
75
50 Chla (ug/L)
25
0 J F M A M J J A S O N D Years 2002-2003 Figure A14. Nutrient and Chlorophyll-a TMDL Results (2002-2003) Leipsic River (Tidal) - DE160-001 Lower Leipsic River, Station 202021 (11,12) 40% NPS Reduction of N/P/C
(Calibration Run L12, TMDL Run L14) A-14 Open Bar - Calibration/Validation, Filled Bar - TMDL 5
4
3
2 TN (mg/L)
1
0 J F M A M J J A S O N D
Open Bar - Calibration/Validation, Filled Bar - TMDL 0.50
0.40
0.30
0.20 TP (mg/L)
0.10
0.00 J F M A M J J A S O N D
Open Bar - Calibration/Validation, Filled Bar - TMDL 150
125
100
75
50 Chla (ug/L)
25
0 J F M A M J J A S O N D Years 2002-2003 Figure A15. Nutrient and Chlorophyll-a TMDL Results (2002-2003) Leipsic River (Tidal) - DE160-001 Lower Leipsic River, Station 202181 (17,26) 40% NPS Reduction of N/P/C
(Calibration Run L12, TMDL Run L14) A-15 Open Bar - Calibration/Validation, Filled Bar - TMDL 5
4
3
2 TN (mg/L)
1
0 J F M A M J J A S O N D
Open Bar - Calibration/Validation, Filled Bar - TMDL 0.50
0.40
0.30
0.20 TP (mg/L)
0.10
0.00 J F M A M J J A S O N D
Open Bar - Calibration/Validation, Filled Bar - TMDL 150
125
100
75
50 Chla (ug/L)
25
0 J F M A M J J A S O N D Years 2002-2003 Figure A16. Nutrient and Chlorophyll-a TMDL Results (2002-2003) Leipsic River (Tidal) - DE160-001 Lower Leipsic River, Station 202031 (20,24) 40% NPS Reduction of N/P/C
(Calibration Run L12, TMDL Run L14) A-16 Open Bar - Calibration/Validation, Filled Bar - TMDL 5
4
3
2 TN (mg/L)
1
0 J F M A M J J A S O N D
Open Bar - Calibration/Validation, Filled Bar - TMDL 0.50
0.40
0.30
0.20 TP (mg/L)
0.10
0.00 J F M A M J J A S O N D
Open Bar - Calibration/Validation, Filled Bar - TMDL 150
125
100
75
50 Chla (ug/L)
25
0 J F M A M J J A S O N D Years 2002-2003 Figure A17. Nutrient and Chlorophyll-a TMDL Results (2002-2003) Leipsic River (Tidal) - DE160-001 Lower Leipsic River, Station 202161 (21,8) 40% NPS Reduction of N/P/C
(Calibration Run L12, TMDL Run L14) A-17 Filled Bar - Calibration/Validation, Open Bar - TMDL 15
10
5 DO (mg/L)
0 J F M A M J J A S O N D 2002-2003 10000
1000
100 Geometric Mean Stnd
10 Enterococcus (#/100mL)
Solid - Calibration/Validation Dashed - TMDL Results 1 0.1 1 10 20 50 80 90 99 99.9 % Less than or Equal to
Leipsic River (Tidal) - DE160-001 Lower Leipsic River, Station 202021 (11,12) Figure A18. DO and Enterococcus TMDL Results (2002-2003) 40% NPS Reduction of N/P/C, 75% NPS Reduction of Bacteria
(Eutro Calibration Run L12, Eutro TMDL Run L14, Pathogen Calibration Run L7, Pathogen TMDL Run L10)
A-18 Filled Bar - Calibration/Validation, Open Bar - TMDL 15
10
5 DO (mg/L)
0 J F M A M J J A S O N D 2002-2003 10000
1000
100
Geometric Mean Stnd
10 Enterococcus (#/100mL)
Solid - Calibration/Validation Dashed - TMDL Results 1 0.1 1 10 20 50 80 90 99 99.9 % Less than or Equal to
Leipsic River (Tidal) - DE160-001 Lower Leipsic River, Station 202181 (17,26) Figure A19. DO and Enterococcus TMDL Results (2002-2003) 40% NPS Reduction of N/P/C, 75% NPS Reduction of Bacteria
(Eutro Calibration Run L12, Eutro TMDL Run L14, Pathogen Calibration Run L7, Pathogen TMDL Run L10)
A-19 Filled Bar - Calibration/Validation, Open Bar - TMDL 15
10
5 DO (mg/L)
0 J F M A M J J A S O N D 2002-2003 10000
1000
100
Geometric Mean Stnd
10 Enterococcus (#/100mL)
Solid - Calibration/Validation Dashed - TMDL Results 1 0.1 1 10 20 50 80 90 99 99.9 % Less than or Equal to
Leipsic River (Tidal) - DE160-001 Lower Leipsic River, Station 202031 (20,24) Figure A20. DO and Enterococcus TMDL Results (2002-2003) 40% NPS Reduction of N/P/C, 75% NPS Reduction of Bacteria
(Eutro Calibration Run L12, Eutro TMDL Run L14, Pathogen Calibration Run L7, Pathogen TMDL Run L10)
A-20 Filled Bar - Calibration/Validation, Open Bar - TMDL 15
10
5 DO (mg/L)
0 J F M A M J J A S O N D 2002-2003 10000
1000
100
Geometric Mean Stnd
10 Enterococcus (#/100mL)
Solid - Calibration/Validation Dashed - TMDL Results 1 0.1 1 10 20 50 80 90 99 99.9 % Less than or Equal to
Leipsic River (Tidal) - DE160-001 Lower Leipsic River, Station 202161 (21,8) Figure A21. DO and Enterococcus TMDL Results (2002-2003) 40% NPS Reduction of N/P/C, 75% NPS Reduction of Bacteria
(Eutro Calibration Run L12, Eutro TMDL Run L14, Pathogen Calibration Run L7, Pathogen TMDL Run L10)
A-21
APPENDIX 3 LEIPSIC RIVER BASELINE LOADINGS
TABLE A1 Baseline Loads For The Leipsic River Watershed
Parameter WLA LA Total TN (lb/d) 0.0 932.26 932.26 TP (lb/d) 0.0 103.29 103.29 Enterococcus (#/d) 0.0 4.33E+11 4.33E+11
A-22
TABLE A2 Leipsic River Baseline NPS Loads by Land Use and Watershed Group Parameter Urban Agriculture Pasture Forest Wetlands Total Lower Leipsic River Area (acres) 1,161 6,653 160 1,012 2,549 11,535 TN (lb/d) 124.09 148.27 6.68 8.10 23.40 310.54 TP (lb/d) 14.33 9.14 0.45 1.19 11.08 36.18 Enterococcus (#/d) 1.20E+11 4.35E+08 1.08E+09 1.79E+07 0.00E+00 1.22E+11 Upper Leipsic River Area (acres) 1,435 7,366 141 1,096 1,052 11,091 TN (lb/d) 153.34 164.16 5.81 8.78 9.66 341.76 TP (lb/d) 17.71 10.12 0.39 1.28 4.57 34.08 Enterococcus (#/d) 1.49E+11 4.81E+08 9.93E+08 1.94E+07 0.00E+00 1.50E+11 Muddy Branch Area (acres) 676 2,011 84 434 1,120 4,325 TN (lb/d) 72.23 44.83 4.14 3.47 10.28 134.94 TP (lb/d) 8.34 2.76 0.27 0.51 4.87 16.75 Enterococcus (#/d) 7.01E+10 1.31E+08 1.17E+08 7.66E+06 0.00E+00 7.04E+10 Dyke Branch Area (acres) 866 1,953 25 401 550 3,794 TN (lb/d) 92.50 43.53 0.74 3.21 5.05 145.02 TP (lb/d) 10.68 2.68 0.05 0.47 2.39 16.28 Enterococcus (#/d) 8.98E+10 1.28E+08 3.84E+08 7.08E+06 0.00E+00 9.03E+10
A-23
APPENDIX 4 LEIPSIC RIVER LSPC INPUTS (ACCUMULATION RATES AND LIMITS)
TABLE A3
Leipsic River Watershed LSPC Accumulation Rates (lb/acre/day) - Calibration Run
Pasture/ Urban Urban Pollutant Agriculture Forest Wetlands Other Rangeland Pervious Impervious BOD 5.0 2.5 3.5 15.0 0.2 2.5 5.0 Organic Nitrogen 2.00 1.00 1.40 6.00 0.08 1.00 2.00 Ammonia 0.750 0.045 0.150 0.100 0.015 0.045 0.100 Nitrite plus Nitrate 9.00 1.00 3.00 5.00 0.06 1.00 3.00 Organic Phosporus 0.750 0.300 0.400 2.000 0.030 0.300 0.750 Phosphate 0.0300 0.0150 0.0200 0.0500 0.0068 0.0140 0.0200 Enterococcus 2.30E+08 6.59E+07 2.30E+10 8.70E+08 8.70E+08 0.00E+00 0.00E+00
TABLE A4
Leipsic River Watershed LSPC Accumulation Limits (lb/acre) - Calibration Run
Pasture/ Urban Urban Pollutant Agriculture Forest Wetlands Other Rangeland Pervious Impervious BOD 10.0 5.0 7.0 30.0 0.4 5.0 10.0 Organic Nitrogen 4.00 2.00 2.80 12.00 0.16 2.00 4.00 Ammonia 7.500 0.450 0.300 1.000 0.150 0.450 1.000 Nitrite plus Nitrate 90.00 10.00 30.00 50.00 0.60 10.00 30.00 Organic Phosporus 1.500 0.600 0.800 4.000 0.060 0.600 1.500 Phosphate 0.3000 0.1500 0.2000 0.5000 0.0320 0.1400 0.2000 Enterococcus 4.15E+08 1.19E+08 4.15E+10 1.57E+09 1.57E+09 0.00E+00 0.00E+00
A-24